System, device, and method for mixing liquids

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application may include subject matter related to one or more of the following commonly-owned United States patent applications, each of which was filed on even date herewith and is hereby incorporated herein by reference in its entirety: U.S. patent application Ser. No. 10/696,969 entitled SYSTEM, DEVICE, AND METHOD FOR MIXING A SUBSTANCE WITH A LIQUID (referred to herein as “Application D70”); U.S. patent application Ser. No. 10/696,818, now U.S. Pat. No. 7,086,700 entitled TWO-STAGE MIXING SYSTEM, APPARATUS, AND METHOD (referred to herein as “Application D72”); U.S. patent application Ser. No. 10/697,176 entitled SYSTEM AND METHOD FOR PUMPING FLUID USING A PUMP CASSETE (referred to herein as “Application D73”); U.S. patent application Ser. No. 10/696,984 entitled DOOR LOCKING MECHANISM (referred to herein as “Application D74”); U.S. patent application Ser. No. 10/697,450 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL (referred to herein as “Application D75”); U.S. patent application Ser. No. 10/697,862 entitled PUMP CASSETE WITH SPIKING ASSEMBLY (referred to herein as “Application D84”); and U.S. patent application Ser. No. 10/696,990 entitled PUMP CASSETTE BANK (referred to herein as “Application D85”).

FIELD OF THE INVENTION

The present invention relates generally to pumping liquids, and more particularly to a system, device, and method for mixing liquids.

BACKGROUND OF THE INVENTION

Millions of people receive blood transfusions each year. Although helpful in many cases, blood transfusions have associated risks. Among others, there is a risk that microorganisms capable of causing disease (i.e., pathogens) could pass from the donor blood to the ultimate blood recipient. For example, untreated blood used in a blood transfusion could have pathogens causing the West Nile Virus, or AIDS. It thus is critical for the public health to ensure that transfused blood is substantially free of pathogens.

The medical community has responded to this need by developing various techniques for removing known and unknown pathogens from donated blood. One technique involves mixing precise amounts of a diluted anti-pathogen compound with blood. Some time after mixing, a rinsing process removes the anti-pathogen compound from the blood. One complexity with this process, however, is the fact that the diluted anti-pathogen compound has a very short shelf life (e.g., on the order of about four hours). Accordingly, the diluted anti-pathogen compound must be produced a relatively short time before it is mixed with blood.

The anti-pathogen compound is not easy to handle before it is diluted. To the contrary, it has a very high pH (e.g., on the order of 11.0 or higher) and thus, is highly caustic and toxic. Mere contact with the undiluted solution can melt plastic, or burn flesh. Because of these undesirable properties, the undiluted solution typically is manually diluted by highly trained laboratory technicians that necessarily must be protected from direct contact with it. Consequently, laboratory technicians often are required to wear relatively impermeable protective gear while diluting the solution behind a chemical laminar flowhood. Such a process, however, is inherently slow, imprecise, and costly due to the multitude of safety requirements. Moreover, even with safeguards, diluting the undiluted solution still poses a risk to the laboratory technician.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, mixing liquids involves pumping a first liquid into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus and pumping a second liquid from a second pump chamber of the pumping apparatus into either the channel or the first pump chamber, preferably while the first liquid is being pumped into the first pump chamber, so that the two liquids are mixed within the pumping apparatus. The second liquid is preferably pumped in a pulsatile mode in which small quantities of the second liquid are pumped at intervals. The quantity and/or the interval can be dynamically adjusted to result in a predetermined concentration of the two liquids. The contents of the first pump chamber are pumped to a receptacle.

In accordance with another aspect of the invention, a method for mixing a first liquid with a second liquid involves pumping a first liquid into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus and pumping a quantity of a second liquid from a second pump chamber of the pumping apparatus into one of the channel and the first pump chamber so as to mix the first liquid and the second liquid within the pumping apparatus. The quantity of the second liquid is preferably pumped during the pumping of the first liquid. The pumping apparatus may be a pneumatically operated pump cassette having various pneumatically operated pump chambers and valves. The second liquid may be pumped in a pulsatile mode. The pulse width and pulse interval may be dynamically adjusted to obtain a predetermined concentration of first liquid and second liquid. The contents of the first pump chamber may be pumped to a receptacle.

In accordance with another aspect of the present invention, an apparatus for mixing a first liquid with a second liquid includes a first pump controller operatively coupled to pump a first liquid into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus and a second pump controller operatively coupled to pump a quantity of a second liquid from a second pump chamber of the pumping apparatus into one of the channel and the first pump chamber so as to mix the first liquid and the second liquid within the pumping apparatus. The quantity of the second liquid is preferably pumped during the pumping of the first liquid. The pumping apparatus may be a pneumatically operated pump cassette having various pneumatically operated pump chambers and valves. The second liquid may be pumped in a pulsatile mode. The pulse width and pulse interval may be dynamically adjusted to obtain a predetermined concentration of first liquid and second liquid. The contents of the first pump chamber may be pumped to a receptacle. The apparatus may include a pump cassette interface for pneumatically operating the chambers and valves of the pump cassette. The pump cassette interface may include a limiter for limiting the amount of second liquid held by the second pump chamber.

In accordance with another aspect of the present invention, an apparatus for mixing a first liquid with a second liquid includes means for pumping a first liquid into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus and means for pumping a quantity of a second liquid from a second pump chamber of the pumping apparatus into one of the channel and the first pump chamber so as to mix the first liquid and the second liquid within the pumping apparatus.

In accordance with another aspect of the present invention, a system for mixing a first liquid with a second liquid includes a plurality of first liquid containers, each containing a first liquid; a second liquid container containing a second liquid; and a plurality of pumps, each pump operatively coupled to mix first liquid from a respective one of the plurality of first liquid containers with second liquid from the second liquid container. The system may also include a process controller in communication with the plurality of pumps for coordinating said mixing by the pumps.

In accordance with another aspect of the invention, red blood cell concentrate is mixed with an anti-pathogen solution to form an incubation solution.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

<figref idref="DRAWINGS">FIG. 1A</figref> shows an exemplary blood processing system having a plurality of blood pumps in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 1B</figref> shows an exemplary wiring diagram for one embodiment of the blood processing system shown in <figref idref="DRAWINGS">FIG. 1A</figref>;

<figref idref="DRAWINGS">FIG. 1C</figref> shows an exemplary wiring diagram for another embodiment of the blood processing system shown in <figref idref="DRAWINGS">FIG. 1A</figref>;

<figref idref="DRAWINGS">FIG. 2</figref> shows an exemplary blood disposables set in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 3A</figref> shows a front view of the pump cassette in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 3B</figref> shows a rear view of the pump cassette in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 4</figref> shows a conceptual block diagram of the blood pump in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 5A</figref> is an architectural flow diagram showing the relationship between the pneumatic control assembly and the other assemblies in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 5B</figref> shows an exemplary embodiment of the pneumatic control assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 5C</figref> shows an exemplary embodiment of the air pump in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 6A</figref> shows an exploded view of an exemplary front plate assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 6B</figref> shows a front view of an exemplary bezel in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 6C</figref> shows a rear view of an exemplary bezel in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 6D</figref> shows a front view of an exemplary bezel gasket in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 6E</figref> shows a rear view of an exemplary bezel gasket in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 7A</figref> shows an exploded view of the door assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 7B</figref> shows a front perspective view of the door assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 7C</figref> shows a rear perspective view of the door assembly in accordance with an embodiment of the present invention, in which the cassette receptacle is in a retracted position;

<figref idref="DRAWINGS">FIG. 7D</figref> shows a rear perspective view of the door assembly in accordance with an embodiment of the present invention, in which the cassette receptacle is in an open position;

<figref idref="DRAWINGS">FIG. 8</figref> shows a side perspective view of the occluder assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 9</figref> shows a cross-sectional view of an occluder in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 10</figref> shows an exploded view of the occluder assembly in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 11</figref> is a schematic diagram showing the pump cassette installed in the blood pump in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 12</figref> shows a process flow diagram describing the compounding and blood treatment process, which is coordinated by the process controller, in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIGS. 13A-B</figref> show a process flow diagram showing additional details of the blood processing operations in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 14</figref> shows a process flow diagram describing the blood pump dry CIT process in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 15</figref> shows a process flow diagram describing the blood pump working solution priming process in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 16</figref> shows a process flow diagram describing the blood pump wet CIT process in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIGS. 17A-D</figref> show a process flow diagram describing the blood mixing process in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 18</figref> shows a process flow diagram describing the volumetric calibration process in accordance with an embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 19</figref> shows a process flow diagram describing the process for manual blood pump teardown in accordance with an embodiment of the present invention; and

<figref idref="DRAWINGS">FIG. 20</figref> shows a logic flow diagram showing exemplary logic <b>2000</b> for mixing two liquids in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Embodiments of the present invention provide for safely and efficiently mixing two liquids. In order to mix two liquids, a first liquid is pumped into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus. A second liquid is pumped from a second pump chamber of the pumping apparatus into either the channel or the first pump chamber, preferably while the first liquid is being pumped into the first pump chamber. In this way, the two liquids are mixed within the pumping apparatus, and, more specifically, within the channel and/or the first pump chamber of the pumping apparatus. The second liquid is preferably pumped in a pulsatile mode in which small quantities of the second liquid are pumped at intervals, for example, as described in U.S. Pat. No. 6,604,908, which is hereby incorporated herein by reference in its entirety. The quantity and/or the interval can be dynamically adjusted to result in a predetermined concentration of the two liquids. The contents of the first pump chamber are pumped to a receptacle.

<figref idref="DRAWINGS">FIG. 20</figref> is a logic flow diagram showing exemplary logic <b>2000</b> for mixing two liquids in accordance with an embodiment of the present invention. Beginning in block <b>2002</b>, the logic pumps a first liquid into a first pump chamber of a pumping apparatus through a channel of the pumping apparatus, in block <b>2004</b>. The logic pumps a second liquid from a second pump chamber of the pumping apparatus into one of the channel and the first pump chamber so as to mix the first liquid and the second liquid within the pumping apparatus, in block <b>2006</b>. The logic dynamically adjusts the amount of second liquid pumped to obtain a predetermined concentration of first liquid and second liquid, in block <b>2008</b>. The logic pumps the contents of the first pump chamber into a receptacle, in block <b>2010</b>. The various pumping and adjusting operations may be repeated as necessary to process a predetermined quantity of liquids. The logic <b>2000</b> ends in block <b>2099</b>.

In exemplary embodiments of the present invention, the pumping apparatus is a disposable pump cassette. The pump cassette typically includes two pump chambers and various valves. The pump chambers and valves are preferably operated pneumatically.

In exemplary embodiments of the present invention, an anti-pathogen solution is mixed with a red blood cell concentrate (RBCC) to form an incubation solution for reducing pathogens in the RBCC. The anti-pathogen solution is prepared by mixing a caustic anti-pathogen compound known as PEN110 or INACTINE, which is an organic solvent with a pH over 11 that is distributed by V.I. Technologies, Inc. of Watertown, Mass., with a buffer solution of sodium phosphate to a predetermined concentration (e.g., 1 part anti-pathogen compound to 99 parts buffer solution), preferably as described in Application D70. For convenience, this mixing of anti-pathogen compound with buffer solution may be referred to hereinafter as “compounding,” and an apparatus that performs such compounding may be referred to hereinafter as a “compounder” or “compounder pump.” The incubation solution is prepared by mixing the anti-pathogen solution with the RBCC to a predetermined concentration (e.g., 1 part anti-pathogen solution to 9 parts RBCC), as described below. For convenience, this mixing of anti-pathogen solution with RBCC may be referred to hereinafter as “blood processing,” and an apparatus that performs such blood processing may be referred to hereinafter as a “blood pump.”

System Overview

<figref idref="DRAWINGS">FIG. 1A</figref> shows an exemplary blood processing system <b>100</b> having a plurality of blood pumps in accordance with an embodiment of the present invention. Among other things, the blood processing system <b>100</b> includes a single compounder pump <b>102</b> and ten essentially identical blood pumps <b>104</b> organized as two banks of five blood pumps each. The compounder pump <b>102</b> pumps buffer solution from a buffer solution container <b>110</b> into a vial of anti-pathogen compound <b>108</b>. The mixture, referred to as a working solution, is pumped into a working solution container <b>112</b>. Each of the blood pumps <b>104</b> mixes working solution from the working solution container <b>112</b> with red blood cell concentrate (RBCC) from a RBCC container <b>106</b> to form an incubation solution that is pumped into an incubation bag <b>118</b>. The incubation solution is typically allowed to incubate for some period of time, after which it is rinsed to remove the anti-pathogen compound to produce a pathogen reduced blood product. The blood processing system <b>100</b> typically also includes two sterile docks <b>114</b> that are used by the operator to splice together plastic tubing as necessary for various blood processing operations. The blood processing system <b>100</b> is controlled through a user interface <b>116</b>.

<figref idref="DRAWINGS">FIG. 1B</figref> shows an exemplary wiring diagram for one embodiment of the blood processing system <b>100</b>. The compounder pump <b>102</b> and the blood pumps <b>104</b> are typically powered from a common 12-Volt external power supply <b>126</b>, and are controlled by an external process controller <b>120</b>. The process controller <b>120</b> includes the user interface <b>116</b>, a computer <b>122</b>, and a serial port concentrator <b>124</b>. The compounder pump <b>102</b> and the blood pumps <b>104</b> are in communication with the process controller <b>120</b> through the serial port concentrator <b>124</b>, for example, over RS-232 communication links. The blood processing system <b>100</b> typically includes a tubing sealer <b>130</b> for sealing plastic tubing as necessary for various blood processing operations. The blood processing system <b>100</b> typically includes an uninterruptible power supply (UPS) <b>128</b> for maintaining electrical power to the 12-Volt power supply, the process controller, and other components in the event of a primary power loss.

<figref idref="DRAWINGS">FIG. 1C</figref> shows an exemplary wiring diagram for another embodiment of the blood processing system <b>100</b>. The blood processing system <b>100</b> may include a printer in communication with the process controller for printing out reports. The blood processing system <b>100</b> may include a card reader <b>134</b> in communication with the process controller for card-based operator identification. The blood processing system <b>100</b> may include a wireless bar code scanner base station <b>138</b> in communication with the process controller for receiving bar code information scanned using a wireless bar code scanner <b>136</b>. Bar codes are typically used to track the various solution containers and the pumps on which those containers were processed.

The process controller <b>120</b> coordinates the actions of the compounder pump <b>102</b>, the blood pumps <b>104</b>, and the operator throughout the various mixing operations, as described in greater detail in Application D72. The process controller <b>120</b> initiates high level embedded commands within the pumps to move and mix the fluids. The process controller <b>120</b> instructs the operator through the setup and teardown of each process through the user interface <b>116</b>. The user interface <b>116</b> is also used to inform the operator of any anomalies that may occur during mixing operations.

When the blood processing system <b>100</b> is operating from the uninterruptible power supply <b>128</b> and at other appropriate times, the process controller <b>120</b> will prevent compounding and other pump operations from starting, although the pumps will generally be allowed to complete any ongoing operations. Furthermore, if the process controller fails, the pumps have internal logic for safely completing or terminating any ongoing operations.

Blood Disposables

In an exemplary embodiment of the present invention, the process controller <b>120</b> coordinates blood processing for an entire bank of five blood pumps <b>104</b> at a time. Specifically, five pump cassettes, each connected to a RBCC container and an incubation bag for receiving the incubation solution, are loaded respectively into the five blood pumps <b>104</b>. The five pump cassettes are preferably connected by a single working solution inlet tube to the working solution container so that all five blood pumps draw working solution from the single working solution container. For convenience, the five interconnected pump cassettes along with their respective incubation bags and various plastic tubing may be referred to hereinafter as a “blood disposables set.” The blood disposables set is preferably used for a single blood processing cycle and is then discarded. The blood disposables set is described in greater detail in Application D85.

<figref idref="DRAWINGS">FIG. 2</figref> shows an exemplary blood disposables set <b>200</b> in accordance with an embodiment of the present invention. The blood disposables set <b>200</b> includes five pump cassettes <b>202</b>_1-5, each respectively having a RBCC inlet tube <b>204</b>_1-5connected to an RBC inlet port of the pump cassette and an incubation solution outlet tube <b>206</b>_1-5connected to an outlet port of the pump cassette and to an incubation-bag <b>118</b>_1-5. The blood disposables set <b>200</b> also includes working solution distribution tubing <b>212</b> that connects to a working solution inlet port on each pump cassette <b>202</b>_1-5and to a single working solution inlet tube <b>210</b> so that the working solution inlet ports of all pump cassettes <b>202</b>_1-5are effectively connected to the single working solution inlet tube <b>210</b>. The working solution inlet tube <b>210</b> preferably connects to the working solution distribution tubing <b>212</b> close to where the working solution inlet port of the middle pump cassette <b>202</b>₃connects to the tubing <b>212</b>, and the working solution inlet ports of each concentric pair of pump cassettes is preferably connected to the tubing <b>212</b> a substantially equal distance from that center connection such that the working solution inlet ports of the pump cassettes <b>202</b>₁and <b>202</b>₅are essentially equidistant from the center connection and the working solution inlet ports of the pump cassettes <b>202</b>₂and <b>202</b>₄are essentially equidistant from the center connection. Among other things, this spacing of pump cassettes along the tubing <b>212</b> facilitates priming of the pumps, as discussed below. In order to perform blood processing, each RBCC inlet tube <b>204</b> is connected to a separate RBCC container <b>106</b>, and the working solution inlet tube <b>210</b> is connected to the common working solution container <b>112</b>. The blood disposables set <b>200</b> also includes six break-away closures <b>214</b>, one on each of the RBCC inlet tubes <b>204</b> and one on the working solution inlet tube <b>210</b>. In order to reduce the likelihood of confusing which RBCC bag and which incubation bag is associated with each pump cassette, the RBCC inlet tubes <b>204</b> and the incubation solution outlet tubes <b>206</b> are preferably coded, for example, by alternating between color-striped and clear tubing from cassette to cassette.

<figref idref="DRAWINGS">FIG. 3A</figref> shows a front view of the pump cassette <b>202</b> in accordance with an embodiment of the present invention. The pump cassette <b>202</b> is essentially a rigid core including formations and sealing ribs <b>340</b> constituting various pumping chambers, fluid valves, and fluid pathways (channels). The rigid core is covered on each side by a flexible membrane (e.g., a flexible PVC sheet). The flexible membranes seal against the core and isolate the blood pump <b>104</b> from fluids within the cassette. The pump cassette <b>202</b> is designed to interface with the blood pump <b>104</b> in only one direction. For example, the pump cassette <b>202</b> typically includes an asymmetric feature (such as the placement of tubing) that prevents the blood pump door from closing if the pump cassette <b>202</b> is inserted incorrectly.

Among other things, the pump cassette <b>202</b> includes a working solution inlet port <b>304</b>, an RBC inlet port <b>305</b>, a vent port <b>307</b>, an outlet port <b>308</b> and two pumping chambers, namely a working solution chamber <b>333</b> and an RBC chamber <b>334</b>. During blood processing, working solution from the working solution container <b>112</b> is drawn into the working solution chamber <b>333</b> through the tubing <b>210</b> and <b>212</b> and the working solution inlet port <b>304</b>, and is pumped from the working solution chamber <b>333</b> into the channel <b>310</b> while RBCC from the RBCC container <b>106</b> is drawn into the RBC chamber <b>334</b> through the RBCC inlet tube <b>204</b>, the RBCC inlet port <b>305</b>, and the channel <b>310</b>. This causes the working solution and RBCC to be mixed within the channel <b>310</b> and the RBC chamber <b>334</b>. The mixture (incubation solution) is pumped from the RBC chamber <b>334</b> to the incubation bag <b>118</b> through the outlet port <b>308</b> and the incubation solution outlet tube <b>206</b>.

<figref idref="DRAWINGS">FIG. 3B</figref> shows a rear view of the pump cassette <b>202</b> in accordance with an embodiment of the present invention. The rears view of the pump cassette <b>202</b> shows various “volcano” valves that are used to open and close various fluid pathways within the pump cassette <b>202</b>. The valves include an RBC priming valve <b>326</b>, an RBC valve <b>328</b>, an incubation bag valve <b>330</b>, a working solution valve <b>332</b>, and a working solution connection to RBC line valve <b>336</b>. The volcano valves and the pumping chambers are all operated pneumatically from the rear of the pump cassette <b>202</b>, as discussed below.

Blood Pump

As discussed above, each blood pump <b>104</b> prepares incubation solution by mixing an anti-pathogen solution with RBCC. A disposable pump cassette <b>202</b> is used to handle the various fluids. The pump cassette <b>202</b> serves as an interface between the blood pump <b>104</b>, the RBCC container <b>106</b>, and the incubation bag <b>118</b> so that no working solution, RBCC, or incubation solution comes into actual contact with the components of the blood pump <b>104</b>. The blood pump <b>104</b> preferably uses pneumatics to operate the pump cassette <b>202</b> as well as other components, as discussed below.

The blood pump <b>104</b> produces the incubation solution by causing working solution to be drawn into the working solution chamber <b>333</b> and pumping working solution from the working solution chamber <b>333</b> into the channel <b>310</b> while drawing RBCC into the RBC chamber <b>334</b> through the channel <b>310</b>. This causes the working solution and RBCC to be mixed within the channel <b>310</b> and the RBC chamber <b>334</b>. The mixture (incubation solution) is pumped from the RBC chamber <b>334</b> to the incubation bag <b>118</b> through the outlet port <b>308</b>.

In a typical embodiment of the present invention, the working solution is pumped from the working solution chamber <b>333</b> using a pulsing technique in which small quantities of working solution are pumped at predetermined intervals and the pulsing of working solution is adjusted periodically using a closed feedback loop in order to produce an incubation solution having a predetermined concentration of working solution, with predetermined limits. Specifically, the working solution is delivered in a pulsatile mode where the pulse width of the exit valve on the working solution chamber is controlled. The fluid valve is pulsed at a pulse width and interval that is predetermined for each pumping stroke and is adjusted stroke-by-stroke according to the amounts of working solution and RBCC pumped, as described below. The blood pump <b>104</b> can support pulse widths above some minimum value, and the interval between pulses is increased in order to achieve an effective pulse width below the minimum value.

The blood pump <b>104</b> preferably includes a library of generic pump control (N-Pump) functions. The N-Pump library functions are used to perform various generic pumping operations such as, for example, pumping fluid into a chamber of the pump cassette, pumping fluid out of a chamber of the pump cassette, measuring the mount of fluid pumped, performing air detection, and maintaining tank pressures. The blood pump <b>104</b> preferably also includes a Fluid Logic Module (FLM) that contains higher level functions that employ the N-Pump library functions to implement application-specific functions (such as specific logic for mixing the working solution with the RBCC to produce the incubation solution).

The blood pump <b>104</b> includes one master board connected to two pump boards that together perform the N-Pump and FLM functions. The master board communicates to each of the pump boards via a multi-drop RS-485 bus. Each pump board controls a single pump chamber of the pump cassette <b>202</b> and the valves on its board.

<figref idref="DRAWINGS">FIG. 4</figref> shows a conceptual block diagram of the blood pump <b>104</b> in accordance with an embodiment of the present invention. Among other things, the blood pump <b>104</b> includes a door assembly <b>402</b>, an occluder assembly <b>404</b>, a front plate assembly <b>408</b>, a pneumatic control assembly <b>410</b>, a power/communication interface <b>412</b> including connectors for the 12-Volt power supply and the RS-232 communication link to the process controller <b>120</b>, and chassis components <b>414</b>. Each of these assemblies is discussed below.

Pneumatic Control Assembly

The pneumatic control assembly <b>410</b> provides positive and negative air pressure for operating the various other pneumatically controlled components and also acts as the general controller for the blood pump <b>104</b>. The pneumatic control assembly <b>410</b> contains three electromechanical pump module assemblies, namely a tank management module assembly and two chamber module assemblies (one for the working solution pump chamber and one for the RBC pump chamber). Each pump module assembly includes an aluminum manifold, pneumatic valves, pneumatic fittings, a valve interface board, and an electronics board that includes pressure transducers and a dedicated microprocessor. The tank management module assembly handles all communication between the blood pump and the process controller <b>120</b>, synchronizes pumping of the chamber module assemblies, maintains positive and negative air pressure in various accumulators, seals and unseals the door assembly, engages and disengages the occluders, monitors the door open/closed status, and monitors the air-in-line sensor, as described below. Each chamber management assembly controls a separate one of the pump chambers, and also controls the fluid valves associated with the pump chamber and measures the volume of liquids pumped through the pump chamber.

<figref idref="DRAWINGS">FIG. 5A</figref> is an architectural flow diagram showing the relationship between the pneumatic control assembly <b>410</b> and the other assemblies in accordance with an embodiment of the present invention. In this figure, the pneumatic control assembly <b>410</b> is represented by master module <b>512</b>, accumulator assembly <b>513</b>, working solution pump module <b>514</b>, and RBCC pump module <b>515</b>. The air pump <b>511</b> is considered to be one of the chassis components <b>414</b>. The air pump <b>511</b> generates high and low air pressure for the master module <b>512</b>, which stores high and low air pressure in the accumulator assembly <b>513</b>. The pneumatic control assembly <b>410</b> directs air pressure (positive and negative) to the various pneumatic mechanisms of the pump. The master module <b>512</b> pneumatically controls bladders in the occluder assembly <b>404</b> and a bladder in the door assembly <b>402</b>, as discussed below. The master module <b>512</b> provides high and low air pressure to the working solution pump module <b>514</b> and the RBCC pump module <b>515</b>. The working solution pump module <b>514</b> controls the working solution chamber <b>333</b> and associated valves of the pump cassette <b>202</b> through the front plate assembly <b>408</b>, and the RBCC pump module <b>515</b> controls the RBC chamber <b>334</b> and associated valves of the pump cassette <b>202</b> through the front plate assembly <b>408</b>, as described below.

<figref idref="DRAWINGS">FIG. 5B</figref> shows an exemplary embodiment of the pneumatic control assembly <b>410</b> in accordance with an embodiment of the present invention. Among other things, the pneumatic control assembly <b>410</b> includes manifold mounting bracket <b>502</b>, a negative pressure accumulator (pressure bottle) <b>513</b><i>a</i>, a positive pressure accumulator (pressure bottle) <b>513</b><i>b</i>, a manual door vent mechanism <b>503</b>, the Tank Management Module Assembly <b>512</b>, the two Chamber Module Assemblies <b>514</b> and <b>515</b>, and associated tubing and fittings.

The tank management module <b>512</b> includes an input/output (I/O) board, a CPU board, a valve-interface board, a pneumatic manifold system, pneumatic valves, pressure transducers 2-vent covers (mufflers), stand-offs, and associated tubing and fittings. The tank management module <b>512</b> is used to control the pressures in the accumulators <b>513</b>, a bladder in the door assembly <b>402</b>, and bladders in the occluder assembly <b>404</b>. The I/O board contains electrical controls for controlling LEDs that provide status information to the operator. The pressure transducers are used to monitor the pressures of the accumulators <b>513</b> and the bladder in the door assembly <b>402</b>.

In the un-powered state, the pneumatic valve that controls flow to the bladder in the door assembly <b>402</b> preferably shuts closed. This prevents the door from being opened in the event of a loss of power.

In the un-powered state, the pneumatic valves that control flow to the bladders in the occluder assembly <b>404</b> are preferably channeled to vent. This causes the occluders to occlude the tubing to prevent further flow of fluid through the tubing, as discussed below.

Each chamber module <b>514</b> and <b>515</b> includes a CPU board, a valve interface board, pneumatic manifold system, pneumatic valves (including a VSO (variable) valve), a VSX chamber (<b>504</b> and <b>505</b> respectively), O-ring, copper mesh, vent cover (muffler), stand-offs, pressure transducers, and associated tubing and fittings. Each chamber module assembly controls the pneumatics for one of the pumping chambers and its associated valves. The VSX chambers <b>504</b> and <b>505</b> act as reference volumes in order to measure the volume of fluid that is delivered with the FMS system. The pressure transducers are used to monitor the pressure of the VSX chamber, and of the pumping chamber. The positive pneumatic system contains a pressure relief valve to prevent the air pump from pressurizing the positive system to greater than 16.0 psig.

In the un-powered state, all of the pneumatic valves preferably open the fluid valves to the positive pressure line. This ensures that the fluid valves are closed if there is a loss of power.

The blood pump <b>104</b> typically includes three microprocessor systems, one on the tank management module <b>512</b> and one on each of the chamber modules <b>514</b> and <b>515</b>. These three microprocessor systems monitor each other for normal operation. Each microprocessor system also monitors key internal processes and data for validity. If any of these monitors fail, a failsafe line permits any of the three processors to stop pumping operations, close all of the fluid valves and occluder, and send an anomaly signal to the process controller. If the blood pump <b>104</b> detects an anomaly with the commands received from the process controller (e.g., commands received out of sequence), then the blood pump <b>104</b> will stop fluid flow and send an anomaly signal to the process controller.

<figref idref="DRAWINGS">FIG. 5C</figref> shows an exemplary embodiment of the air pump <b>511</b> in accordance with an embodiment of the present invention. The air pump <b>511</b> includes a pump motor <b>591</b> mounted to a pump plate <b>592</b> using double-sided tape <b>594</b> and two miniature nylon cable ties <b>595</b>. Four ribbed isolator grommets <b>593</b> are inserted into corresponding openings in the pump plate <b>592</b>.

Front Plate Assembly

The front plate assembly <b>408</b> includes all necessary pneumatic pathways to interface to the disposable pump cassette <b>202</b>. The front plate assembly <b>408</b> includes a bezel and a bezel gasket through which the pump cassette <b>202</b> is operated. During operation of the blood pump <b>104</b>, the pump cassette <b>202</b> is positioned in the door assembly <b>402</b> and is pressed against the front plate assembly <b>408</b> in alignment with the bezel and bezel gasket by a bladder in the door assembly <b>402</b>, as discussed below. Air lines connected to the bezel from the pneumatic control assembly <b>410</b> are used to displace membranes of the bezel gasket to operate the various valves and chambers of the pump cassette <b>202</b>.

<figref idref="DRAWINGS">FIG. 6A</figref> shows an exploded view of an exemplary front plate assembly <b>408</b> in accordance with an embodiment of the present invention. Among other things, the front plate assembly <b>408</b> includes a rigid front plate <b>602</b> to which are mounted a bezel <b>604</b>, chamber foam <b>606</b>, spacer <b>608</b>, air-in-line sensor <b>610</b>, bezel gasket <b>612</b>, gasket retainer <b>614</b>, hardware <b>616</b>, dowel pins <b>618</b>, and grommet <b>620</b>. The bezel <b>604</b>, chamber foam <b>606</b>, and bezel gasket <b>612</b> are mounted to the front plate <b>602</b> by the gasket retainer <b>614</b> and associated hardware <b>616</b>, forming a bezel assembly. This bezel assembly is used to control pumping and mixing of fluids using the pump cassette <b>202</b>, as described below. The front plate <b>602</b> includes holes for allowing air tubes to pass between the rear of the bezel <b>604</b> and the pneumatic control assembly <b>410</b>, which is typically situated behind the front plate <b>602</b>. The front plate <b>602</b> also includes openings for occluder blades and for engaging a door latch mechanism, as described below. The air-in-line sensor <b>610</b> is positioned so as to align with and engage the RBCC inlet tube <b>204</b>, and is used during blood processing to detect air in the RBCC inlet tube <b>204</b> indicating that there is no more RBCC to be processed.

<figref idref="DRAWINGS">FIG. 6B</figref> shows a front view of an exemplary bezel <b>604</b> in accordance with an embodiment of the present invention. The bezel <b>604</b> is preferably a molded polycarbonate/ABS unit including, among other things, a working solution chamber cavity <b>633</b> for operating the working solution chamber <b>333</b> of the pump cassette <b>202</b>, an RBC chamber cavity <b>634</b> for operating the RBC chamber <b>334</b> of the pump cassette <b>202</b>, and various valve cavities <b>635</b> for operating the various valves of the pump cassette <b>202</b>. Each of the chamber cavities <b>633</b> and <b>634</b> typically includes two air holes <b>638</b> through which air is pumped into and out of the chamber cavity. The working solution chamber cavity <b>633</b> is preferably molded with rib structures <b>636</b> that allow for airflow within the working solution chamber cavity <b>633</b> but mechanically restrict the amount of working solution that can be drawn into the working solution chamber <b>333</b> of the pump cassette <b>202</b>. The bezel with rib structures is described in greater detail in Application D75. The compounder <b>102</b> preferably uses the same molded bezel <b>604</b> as the blood pump <b>104</b>, but with the rib structures <b>636</b> removed (e.g., by precision machining) to allow for greater pumping capacity.

<figref idref="DRAWINGS">FIG. 6C</figref> shows a rear view of the bezel <b>604</b> in accordance with an embodiment of the present invention. The bezel <b>604</b> includes integral solvent bondable tubing connections (ports) <b>637</b> to which pneumatic tubing from the pneumatic control assembly <b>410</b> are connected. In this embodiment, each of the valve cavities <b>635</b> is associated with a single integral port <b>637</b>, and each of the chamber cavities <b>633</b> and <b>634</b> are associated with two integral ports <b>637</b>. The integral ports <b>637</b> allow the pneumatic connections to be made without independent fittings and accompanying O-rings.

<figref idref="DRAWINGS">FIG. 6D</figref> shows a front view of an exemplary bezel gasket <b>612</b> in accordance with an embodiment of the present invention. The bezel gasket <b>612</b> fits over the front of the bezel <b>604</b> and acts as an interface between the bezel <b>604</b> and the pump cassette <b>202</b> for sealing the fluid paths of the pump cassette <b>202</b> and for actuating the chambers and valves of the pump cassette <b>202</b>. The pump cassette <b>202</b> is pressed firmly against the front side of the bezel gasket <b>612</b> during blood processing in order to produce an air-tight seal between the bezel gasket <b>612</b> and the pump cassette <b>202</b>. The bezel gasket <b>612</b> includes membranes that correspond to the chamber cavities and valve cavities. Positive and negative air pressure produced through the bezel cavities operate on the bezel gasket membranes, which in turn operate on the chambers and valves of the pump cassette <b>202</b>.

<figref idref="DRAWINGS">FIG. 6E</figref> shows a rear view of an exemplary bezel gasket <b>612</b> in accordance with an embodiment of the present invention. The rear side of the bezel gasket <b>612</b> contacts the front side of the bezel <b>604</b>, and is pressed firmly against the bezel <b>604</b> during blood processing in order to produce an air-tight seal. The bezel gasket <b>612</b> includes membranes that correspond to the chamber cavities and valve cavities. Positive and negative air pressure produced through the bezel cavities operate on the bezel gasket membranes, which in turn operate on the chambers and valves of the pump cassette <b>202</b>.

Door Assembly

The door assembly <b>402</b> mounts to the front plate assembly <b>408</b>, and provides a means to load and align the disposable pump cassette <b>202</b> within the blood pump <b>104</b>. The door assembly <b>402</b> provides a force on the pump cassette <b>202</b> against the bezel assembly of the front plate assembly <b>408</b> in order to provide sealing of the cassette's fluid paths and valves, as described in greater detail in Application D73. The door assembly <b>402</b> includes a special latch system that helps maintain the seal, and also helps prevent accidental opening of the door during blood processing, as described in greater detail in Application D74. The door assembly <b>402</b> also provides a surface for the occluders to function against, as described below.

<figref idref="DRAWINGS">FIG. 7A</figref> shows an exploded view of the door assembly <b>402</b> in accordance with an embodiment of the present invention. Among other things, the door assembly <b>402</b> includes a door cowl <b>701</b>, a latch spring post <b>702</b>, a door latch <b>703</b>, a cassette receptacle <b>704</b>, a back plate <b>705</b>, a latch pin <b>706</b>, a bladder <b>707</b> with an attached pneumatic circuit <b>730</b>, a frame <b>708</b>, a door pin <b>709</b>, a door mounting bracket <b>710</b>, a piston assembly <b>711</b> including a piston plate <b>731</b> and a piston cover <b>732</b>, a human interface board assembly <b>712</b>, double coated tape <b>713</b>, a miniature cable tie <b>714</b>, recessed bumpers <b>715</b>, E-rings <b>722</b>, cable tie mount <b>723</b>, torsion springs <b>724</b> and <b>725</b>, extension spring <b>726</b>, a cassette orientation tab <b>799</b>, and various screws <b>716</b>, <b>717</b>, <b>718</b>, <b>719</b>, <b>720</b>, and <b>721</b>. The human interface board assembly <b>712</b> is mounted to the inside of the door cowl <b>701</b>. The piston assembly <b>711</b> includes a rigid plate <b>731</b> having a protrusion that is covered by the piston cover <b>732</b>. The bladder <b>707</b>, double coated tape <b>713</b>, and piston assembly <b>711</b> are sandwiched between the back plate <b>705</b> and the frame <b>708</b>, which are mechanically coupled together to form a frame assembly <b>750</b>. The door latch <b>703</b> is positioned so that a handle portion is accessible from a front side of the door cowl <b>701</b>. The frame assembly <b>750</b> is mounted to the inside of the door cowl <b>701</b> so that a latch portion of the door latch <b>703</b> protrudes through the frame assembly <b>750</b> and the frame assembly <b>750</b> holds the door latch <b>703</b> in place. The cassette receptacle <b>704</b> is pivotally mounted to the frame <b>708</b> using the door mounting bracket <b>710</b>, the door pin <b>709</b>, and the E-rings <b>722</b>. Recessed bumpers <b>715</b> reduce strain on the door if the door is opened too far or with excessive force. The torsion springs <b>724</b> and <b>725</b> aid the operator in closing the door, as the door has considerable weight due to the many components. The cassette orientation tab <b>799</b> prevents the door from being closed if the pump cassette is oriented incorrectly in the cassette receptacle <b>704</b>.

The bladder <b>707</b> is coupled to, and controlled by, a pneumatic circuit <b>730</b> that provides positive and/or negative air pressure to the bladder <b>707</b>. Positive pressure supplied to the bladder <b>707</b> causes the bladder <b>707</b> to expand in the direction of the frame <b>708</b>. This, in turn, causes the entire piston assembly <b>711</b> to move toward the control assembly <b>408</b>, such that the piston cover <b>732</b> presses against the pump cassette <b>202</b> and/or cassette receptacle <b>704</b>, thereby producing an outward force on the door <b>402</b> away from the control assembly <b>408</b>. Alternatively, supplying negative pressure to the bladder <b>707</b> causes the piston assembly <b>711</b> to move away from the pump cassette <b>202</b> and/or cassette receptacle <b>704</b>, thereby reducing the outward force on the door <b>402</b> away from the control assembly <b>408</b>.

The door assembly is designed to permit single-handed operation, specifically by pulling up on the handle. However, the door latch <b>703</b> is designed so that the door cannot be easily opened when the pump cassette is in place in the cassette receptacle <b>704</b> with the door closed and the bladder <b>707</b> is inflated. Specifically, the latch portions of the door latch <b>703</b> have undercuts that are engaged by recesses in the front plate assembly <b>408</b>. When the pump cassette is in place in the cassette receptacle <b>704</b> with the door closed and the bladder <b>707</b> is inflated so as to push the pump cassette against the bezel components of the front plate assembly <b>408</b>, a sufficient force is generated between the door assembly <b>402</b> and the front plate assembly <b>408</b> to prevent the door handle from being easily lifted. This door locking mechanism is described in greater detail in Application D74.

<figref idref="DRAWINGS">FIG. 7B</figref> shows a front perspective view of the door assembly <b>402</b> in accordance with an embodiment of the present invention. The human interface board assembly <b>712</b> having LEDs and the handle portion of the door latch <b>703</b> are visible from the front of the door cowl <b>701</b>. A portion of the cassette receptacle <b>704</b> and a portion of the pneumatic circuit <b>730</b> are also visible.

<figref idref="DRAWINGS">FIG. 7C</figref> shows a rear perspective view of the door assembly <b>402</b> in accordance with an embodiment of the present invention, in which the cassette receptacle <b>704</b> is in a retracted position. Visible at the rear of the door cowl <b>701</b> are the frame <b>708</b>, the latch portion of the door latch <b>703</b>, the cassette receptacle <b>704</b>, the piston assembly <b>711</b>, the door mounting bracket <b>710</b>, the torsion springs <b>724</b> and <b>725</b>, a portion of the human interface board assembly <b>712</b>, and a portion of the pneumatic circuit <b>730</b>.

<figref idref="DRAWINGS">FIG. 7D</figref> shows a rear perspective view of the door assembly <b>402</b> in accordance with an embodiment of the present invention, in which the cassette receptacle <b>704</b> is in an open position. Visible at the rear of the door cowl <b>701</b> are the frame <b>708</b>, the latch portion of the door latch <b>703</b>, the cassette receptacle <b>704</b>, the piston assembly <b>711</b>, the door mounting bracket <b>710</b>, the torsion springs <b>724</b> and <b>725</b>, a portion of the human interface board assembly <b>712</b>, and a portion of the pneumatic circuit <b>730</b>.

Occluder Assembly

The occluder assembly <b>404</b> mounts to the back of the front plate assembly <b>408</b>, and is used to selectively occlude the RBCC inlet tube <b>204</b>, the incubation solution outlet tube <b>206</b>, and the working solution distribution tube <b>212</b> as needed for testing, blood processing, and protection in the event of a failure. In the blood pump <b>104</b>, the occluder assembly <b>404</b> includes two occluders, one operating on both the RBCC inlet tube <b>204</b> and the incubation solution outlet tube <b>206</b>, and the other operating on the working solution distribution tube <b>212</b>. The occluders are controlled pneumatically, and can be controlled independently.

In a typical embodiment of the present invention, each occluder includes an occluder blade that is operated by a flat spring and an inflatable bladder. The occluder blade is coupled to one end of the spring. When the bladder is deflated, the spring extends the occluder blade into an occluding position, which blocks the passage of fluid through the tube(s). When the bladder is inflated, the bladder bends the spring so as to retract the occluder blade from the occluding position, which enables the passage of fluid through the tube(s). In the event of a loss of pneumatics, the occluder defaults to the occluded position so as to prevent fluid from passing through the tubing.

<figref idref="DRAWINGS">FIG. 8</figref> shows a side perspective view of the occluder assembly <b>404</b> in accordance with an embodiment of the present invention. The occluder assembly <b>404</b> includes, among other things, a bottom housing <b>801</b>, a top housing <b>802</b>, a first occluder having an occluder blade <b>813</b> and other components operated pneumatically through tube <b>803</b>, and a second occluder having an occluder blade <b>814</b> and other components operated pneumatically through tube <b>804</b>. The occluder assembly <b>404</b> is mounted to the front plate assembly <b>408</b>, with the occluder blades <b>813</b> and <b>814</b> protruding through slots in the front plate assembly <b>804</b>. The tubes <b>803</b> and <b>804</b> are connected to the pneumatic control assembly <b>410</b>.

<figref idref="DRAWINGS">FIG. 9</figref> shows a cross-sectional view of an occluder in accordance with an embodiment of the present invention. Among other things, the occluder includes a flat occluder spring <b>812</b> having a rear end coupled to the top housing <b>802</b> and a front end coupled to the occluder blade <b>814</b>, a bladder <b>808</b> situated between the top housing <b>802</b> and the spring <b>812</b>, the tube <b>804</b> coupled to the bladder <b>808</b>, and an adjuster <b>810</b> for adjusting the protrusion of the occluder blade <b>814</b>. When the bladder <b>808</b> is inflated, the occluder spring <b>812</b> is deflected downward at the middle so as to shorten the effective length of the occluder spring <b>812</b> and retract the occluder blade <b>814</b>. When the bladder <b>808</b> is deflated, the occluder spring <b>812</b> extends flat and therefore extends the occluder blade <b>814</b>. The occluder blade <b>814</b> moves within guides (not shown) that allow the spring to extend and retract the occluder blade <b>814</b>.

<figref idref="DRAWINGS">FIG. 10</figref> shows an exploded view of the occluder assembly <b>404</b> in accordance with an embodiment of the present invention. Among other things, the occluder assembly <b>404</b> includes enclosure top <b>802</b>, enclosure bottom <b>810</b>, a first occluder including an occluder blade <b>813</b>, a shaft <b>821</b>, a front bracket <b>819</b>, a rear bracket <b>817</b>, a bladder <b>809</b>, and a tube <b>803</b>, and a second occluder including an occluder blade <b>814</b>, a shaft <b>820</b>, a front bracket <b>818</b>, a rear bracket <b>816</b>, a bladder <b>808</b>, and a tube <b>804</b>. The occluder blade <b>813</b> mounts to the front bracket <b>819</b> via the shaft <b>821</b>, while the occluder blade <b>814</b> mounts to the front bracket <b>818</b> via the shaft <b>820</b>. The rear brackets <b>816</b> and <b>817</b> are mounted to the enclosure top <b>802</b> via shaft <b>825</b>, blocks <b>826</b> and <b>827</b>, and clamps <b>828</b> and <b>829</b>. The rear brackets <b>816</b> and <b>817</b> are held in a substantially fixed position, although the rear brackets <b>816</b> and <b>817</b> are able to rotate about the shaft <b>825</b> as needed for operation of the occluders. The front bracket <b>819</b> is mounted to the enclosure top <b>802</b> via shaft <b>821</b> and sliding blocks <b>823</b> and <b>824</b>, while the front bracket <b>818</b> is mounted to the enclosure top <b>802</b> via shaft <b>820</b> and sliding blocks <b>822</b> and <b>823</b>. The front brackets <b>818</b> and <b>819</b> are able to slide forward and backward along channels formed in the sliding blocks <b>822</b>, <b>823</b>, and <b>824</b> as needed for operation of the occluders. Thus, the blocks <b>826</b> and <b>827</b> constrain the position of the occluder blades and act as bearing surfaces as the rear shaft rotates, and the sliding blocks <b>822</b>, <b>823</b>, and <b>824</b> act as bearing surfaces for the front shafts as the occluder blades are actuated and released. It should be noted that the present invention is not limited to the block-type bearings shown, but rather various types of bushings, bearings, fixed blocks, moving blocks, or any combination thereof could be used to permit rotation of the rear shafts and/or brackets and translational movement of the front shafts. The occluder blades <b>813</b> and <b>814</b> can be manually retracted if necessary. The edge of the occluder blades <b>813</b> and <b>814</b> that engages the tubing are typically rounded so as not to cut or crease the tubing.

Chassis Components

The chassis components <b>414</b> include various mechanical hardware components that are not considered part of the other assemblies. Among other things, the chassis components <b>414</b> include the DC air pump <b>511</b>, a chassis base, a door sensor (and cable), mounting foot grommets, skins (housing), and associated hardware and fasteners. The housing includes a mounting point, on the back of the unit, for the manual piston bladder (door) vent <b>503</b>.

Pump Cassette Handling

<figref idref="DRAWINGS">FIG. 11</figref> is a schematic diagram showing the pump cassette <b>202</b> installed in the blood pump <b>104</b> in accordance with an embodiment of the present invention. The pump cassette <b>202</b> is installed in the cassette receptacle <b>704</b>. The door assembly <b>402</b> will only close if the pump cassette <b>202</b> is oriented correctly in the cassette receptacle <b>704</b>, and will not close if the pump cassette <b>202</b> is inserted backwards so that the tubing connected to the pump cassette <b>202</b> does not align with corresponding channels in the door latch <b>703</b>. When the door assembly <b>402</b> is closed and the bladder in the door assembly <b>402</b> is inflated, the pump cassette <b>202</b> is pressed tightly against the bezel gasket <b>612</b> and gasket retainer <b>614</b> on the front panel assembly <b>408</b>, the RBCC inlet tube <b>204</b> is captured by the air-in-line sensor <b>610</b> on the front plate assembly <b>408</b>, the occluder blade <b>813</b> aligns with and occludes the working solution distribution tube <b>212</b>, and the occluder blade <b>814</b> aligns with and occludes both the RBCC inlet tube <b>204</b> and the incubation solution outlet tube <b>206</b>.

Blood Processing

As discussed above, the compounder <b>102</b> and the blood pumps <b>104</b> operate under control of the process controller <b>120</b>. In exemplary embodiments of the present invention, introduction of the anti-pathogen compound into the RBCC is performed in two stages, a first stage in which the anti-pathogen compound is mixed with buffer solution to a first concentration to form the working solution, and a second stage in which the working solution is mixed with the RBCC to a second concentration to form the incubation solution. The two-stage process is described in more detail in Application D72.

<figref idref="DRAWINGS">FIG. 12</figref> shows a process flow diagram describing the compounding and blood treatment process, which is coordinated by the process controller <b>120</b>, in accordance with an embodiment of the present invention. Rectangular blocks indicate commands sent to the pump by the process controller <b>120</b>. Rounded blocks indicate instructions sent to the operator by the process control <b>120</b>.

The process starts in block <b>1201</b>. In block <b>1202</b>, the process controller instructs the operator to load and scan a compounder disposable set. After the compounder disposable set is loaded into the compounder, the process controller instructs the compounder to run a dry cassette integrity test (CIT) in block <b>1203</b>. Assuming the dry CIT is acceptable, the process controller instructs the operator to hang, scan, and connect the buffer solution bag so that the buffer solution bag is connected to the inlet port of the pump cassette, in block <b>1204</b>. The process controller then instructs the compounder to prime the compounder disposable set, in block <b>1205</b>. The process controller then instructs the compounder to run a wet CIT, in block <b>1206</b>. Assuming the wet CIT is acceptable, the process controller then instructs the operator to scan and load the vial assembly and spike receptacle into the vial spike assembly, in block <b>1207</b>. The process controller then instructs the compounder to spike the vial, in block <b>1208</b>. Once spiking is completed, the process controller instructs the compounder to perform the compounding operation, in block <b>1209</b>. Compounding is described in more detail in Application D70.

After compounding is complete, the process controller coordinates “teardown” of the compounder for removal and disposal of the compounder disposable set from the compounder. Specifically, with reference again to <figref idref="DRAWINGS">FIG. 12</figref>, the process controller instructs the operator to heat seal the working solution line, in block <b>1235</b>, and then agitate and invert the working solution bag, in block <b>1214</b>. The process controller then instructs the operator to heat seal the buffer solution line, in block <b>1227</b>. The process controller then instructs the operator to clamp the lines leading to the vial, in block <b>1228</b>. The process controller then instructs the compounder to release the compounder door, in block <b>1231</b>, which is accomplished by deflating the bladder in the door assembly. The process controller then instructs the compounder to release the bladder pressure on the vial spike (piston), in block <b>1232</b>. The process controller then instructs the operator to remove the compounder disposables from the compounder <b>1233</b>.

After compounder “teardown” is complete, the process controller coordinates the blood processing operations in which the RBCC is mixed with working solution by the blood pumps <b>104</b> in order to produce the incubation solutions. Specifically, in block <b>1210</b>, the process controller <b>120</b> instructs the operator to load and scan a blood disposables set in one of the banks of blood pumps <b>104</b>. The process controller <b>120</b> may instruct the operator to scan, for each blood pump, the RBCC bag <b>106</b>, the blood pump <b>104</b>, and the incubation bag <b>118</b>. The process controller <b>120</b> stores this information so that there is a correlation between each blood pump <b>104</b> and the solutions processed and produced by it. This information can be used, for example, to identify all incubation solutions produced by a particular blood pump <b>104</b> if the blood pump <b>104</b> is found to be defective.

After the blood disposables set is loaded, the process controller <b>120</b> instructs the blood pumps <b>120</b> to perform a dry CIT, in block <b>1212</b>. The dry CIT operation is described in more detail with reference to <figref idref="DRAWINGS">FIG. 14</figref> below. Assuming the dry CIT is successful, the process controller <b>120</b> then instructs the operator to connect the working solution inlet tube <b>210</b> of the blood disposables set to the working solution bag <b>112</b> using the sterile dock <b>114</b>, in block <b>1213</b>, and open the break-away closure on the working solution inlet tube <b>210</b>, in block <b>1215</b>. The process controller <b>120</b> then coordinates working solution priming of the blood pumps <b>104</b>, in block <b>1216</b>, and then performs a wet CIT on each of the blood pumps <b>104</b>, in block <b>1217</b>. The priming and wet CIT operations are described in more detail respectively with reference to <figref idref="DRAWINGS">FIGS. 15 and 16</figref> below. Assuming the wet CIT is successful, the process controller <b>120</b> instructs the operator to open the break-away closures on the RBCC inlet tubes <b>204</b>, in block <b>1218</b>. These break-away closures are not opened earlier in order to prevent contamination of the blood in case of a blood pump failure.

After the break-away closures are opened, the process controller <b>120</b> instructs the blood pumps <b>104</b> to mix the RBCC with the working solution to produce the incubation solutions, in block <b>1219</b>. The blood mixing operation is described in more detail with reference to <figref idref="DRAWINGS">FIG. 17</figref> below.

After blood mixing is complete, the process controller <b>120</b> instructs the operator to heat seal the incubation solution outlet tubes <b>206</b>, in block <b>1220</b>, and to heat seal the working solution distribution tubes <b>212</b>, in block <b>1221</b>. The process controller <b>120</b> then instructs the blood pumps <b>104</b> to test the heat seal on the incubation solution outlet tubes <b>206</b>, in block <b>1223</b>. Assuming the tubes are sealed, the process controller <b>120</b> instructs the blood pumps <b>104</b> to release their respective doors, in block <b>1224</b>. The process controller <b>120</b> then instructs the operator to remove the incubation bags <b>118</b>, in block <b>1225</b>, and to tear down the blood disposables set, in block <b>1226</b>.

If there is enough working solution remaining for another blood processing cycle, then the process may recycle to block <b>1210</b> to coordinate blood processing operations for another bank of blood pumps. If and when the working solution has expired or there is not enough working solution remaining for another blood processing cycle, then the process controller typically instructs the operator to remove the working solution bag, in block <b>1236</b>. The process ends in block <b>1234</b>.

<figref idref="DRAWINGS">FIGS. 13A-B</figref> show a process flow diagram showing additional details of the blood processing operations in accordance with an embodiment of the present invention. The process begins in block <b>1301</b>. A check is first made to confirm that the bank of blood pumps <b>104</b> is configured properly, in block <b>1302</b>. This involves, among other things, confirming that there is communication between the process controller <b>120</b> and the five blood pumps <b>104</b>, confirming that all five blood pumps <b>104</b> are configured to operate as blood pumps, and confirming that all five blood pumps <b>104</b> contain the correct version of embedded software. The process enters anomaly handling, in block <b>1303</b>, if the bank is not configured properly.

If the bank is configured properly, then a determination is made as to whether there is a sufficient quantity of working solution and a sufficient amount of time for performing the blood processing operation, in block <b>1304</b>. If there is no working solution, then the compounder setup and process operation is performed as described in Application D70, in block <b>1308</b>. If there is an insufficient amount of working solution, then the compounder teardown operation is performed as described in Application D70, in block <b>1305</b>, and, in block <b>1306</b>, the operator is given the option to either terminate the blood processing operation, in which case the process ends in block <b>1333</b>, or continue the blood processing operation, in which case the compounder setup and process operation is performed as described in Application D70, in block <b>1308</b>.

If there is a sufficient quantity of working solution in block <b>1304</b>, or after working solution is prepared in block <b>1308</b>, the blood disposables set is loaded into the blood pumps <b>104</b>. If the occluders are engaged, in block <b>1309</b>, then the door is unsealed, in block <b>1310</b>. Once the door is unsealed, the operator is instructed to load the blood disposables set, in block <b>1311</b>, and to close the door. When the door is confirmed to be closed, in block <b>1314</b>, the operator is instructed to scan the RBCC bags, blood pumps, and incubation solution bags, in block <b>1313</b>. When scanning is complete, in block <b>1314</b>, the blood pumps <b>104</b> are instructed to seal their respective doors, in block <b>1315</b>. If a door is unable to be sealed, then the process enters anomaly handling, in block <b>1316</b>, which typically includes instructing the operator to reload the pump cassette. If the door is able to be sealed, then the blood pumps <b>104</b> are instructed to perform the dry CIT, in block <b>1317</b>. If the dry CIT fails, then the process enters anomaly handling, in block <b>1318</b>, which typically involves instructing the operator to reload the pump cassette and running the dry CIT again. If the dry CIT passes, then the operator is instructed to connect the working solution inlet tube <b>210</b> to the working solution bag <b>112</b> using the sterile dock and to open the break-away closure on the working solution line, in block <b>1319</b>. The blood pumps <b>104</b> are then instructed to perform the priming process, in block <b>1320</b>. If the priming process fails, then the process enters anomaly handling, in block <b>1320</b>. If priming is successful, then the blood pumps <b>104</b> are instructed to perform the wet CIT, in block <b>1322</b>. If the wet CIT fails, then the process enters anomaly handling, in block <b>1323</b>. If the wet CIT passes, then the operator is instructed to open the break-away closures on the RBCC inlet tubes, in block <b>1324</b>. The blood pumps <b>104</b> are then instructed to mix the RBCC and the working solution to form incubation solution, in block <b>1325</b>. If there is a failure during mixing, then the process enters anomaly handling, in block <b>1326</b>.

Assuming blood processing is successful, the operator is instructed to heat seal the incubation and working solution lines, in block <b>1327</b>. The blood units <b>104</b> are then instructed to test the seal on the incubation line, in block <b>1328</b>. If the test fails, then the process enters anomaly handling, in block <b>1329</b>.

Assuming the incubation line is sealed, then the blood pumps <b>104</b> are instructed to release their respective doors, in block <b>1330</b>, after which the operator is instructed to teardown the blood disposables set, in block <b>1331</b>. A closed-case file is prepared, in block <b>1332</b>. The process ends in block <b>1333</b>.

Blood Pump Dry Cassette Integrity Test

The dry cassette integrity test (CIT) is used to identify air leaks in the cassette membranes prior to pumping any fluids. Identifying a cassette with a membrane hole will protect the RBCC from being contaminated by a potentially non-sterile cassette, and will reduce the potential of pumping fluid into the blood unit itself. Also, at the time of the dry CIT, an internal pressure transducer calibration check is performed in order to ensure that none of the transducers have failed or drifted out of calibration. Also during the dry CIT, the fluid valve leading to the air vent on the cassette is tested by closing the valve, pressurizing the pump chamber, and observing the pressure decay.

<figref idref="DRAWINGS">FIG. 14</figref> shows a process flow diagram describing the blood pump dry CIT process in accordance with an embodiment of the present invention. The dry CIT process begins in block <b>1401</b>. The positive pneumatic system is first isolated from the cassette and a baseline leak rate for the positive assembly is obtained, specifically by closing the working solution line occluder <b>813</b>, in block <b>1402</b>, opening all fluid valves and closing the variable valves, in block <b>1403</b>, measuring the positive tank leak rate, in block <b>1404</b>, and generating an error signal if the positive tank leak rate is greater than or equal to the predetermined threshold, in block <b>1405</b>.

Then, the negative pneumatic system is isolated from the cassette and a baseline leak rate for the negative assembly is obtained, specifically by closing all fluid valves, in block <b>1407</b>, measuring the positive tank leak rate, in block <b>1408</b>, and generating an error signal if the negative tank leak rate is greater than or equal to a predetermined threshold, in block <b>1409</b>.

Then, the process tests the cassette sheeting of the valves outside of the volcano valves, specifically by opening the working solution line occluder <b>813</b>, in block <b>1410</b>, measuring the positive tank leak rate, in block <b>1411</b>, and generating an error signal if the positive tank leak rate is greater than or equal to a predetermined threshold, in block <b>1412</b>.

Then, the process tests the cassette sheeting at the center of the volcano valves, specifically by opening valves <b>1</b>A<b>1</b> and <b>2</b>A<b>1</b> and all fluid valves, in block <b>1413</b>, measuring the positive and negative tank leak rates, in block <b>1414</b>, and generating an error signal if the positive or negative tank leak rate is greater than or equal to a predetermined threshold, in block <b>1415</b>.

Then, the process verifies calibration of the positive transducers, specifically by isolating the positive transducers and connecting the positive transducers together, in block <b>1416</b>, measuring the positive tank leak rate, in block <b>1417</b>, generating an error signal if the positive tank leak rate is greater than or equal to a predetermined threshold, in block <b>1418</b>, determining whether all positive transducers agree to within a predetermined threshold, in block <b>1419</b>, and generating an error signal if the positive transducers do not agree to within a predetermined threshold, in block <b>1420</b>.

Then, the process verifies calibration of the negative transducers, specifically by isolating the negative transducers and connecting the negative transducers together, in block <b>1421</b>, measuring the negative tank leak rate, in block <b>1422</b>, generating an error signal if the negative tank leak rate is greater than or equal to a predetermined threshold, in block <b>1423</b>, determining whether all negative transducers agree to within a predetermined threshold, in block <b>1424</b>, and generating an error signal if the negative transducers do not agree to within a predetermined threshold, in block <b>1425</b>.

Finally, the process tests integrity of the fluid valve leading to the vent filter, specifically by filling the chamber, in block <b>1426</b>, pressurizing the chamber, in block <b>1427</b>, measuring the chamber leak rate, in block <b>1428</b>, and generating an error signal if the chamber leak rate is greater than or equal a predetermined threshold, in block <b>1429</b>. The dry CIT process ends in block <b>1430</b>.

Blood Pump Priming

The working solution priming process operates on an entire bank of five blood pumps, where all blood pumps share a single working solution line. The working solution priming process is coordinated by the process controller <b>120</b> so as to prevent one pump from drawing in air that is being expelled by another pump, specifically by priming the operating the blood pumps symmetrically from the middle blood pump outward. Each blood pump is responsible for detecting “no flow” conditions during priming and also for detecting air in the working solution chamber of the pump cassette <b>202</b> after the priming operation is complete. The priming process uses two operations, namely a “put” operation and a “get” operation. The “put” operation involves pumping the contents of the working solution chamber of the pump cassette <b>202</b> (air and/or working solution) out through the working solution inlet <b>304</b> to the working solution bag, specifically by applying a positive pressure to the working solution chamber. The “get” operation involves drawing from the working solution inlet <b>304</b>, specifically by applying a negative pressure to the working solution chamber. For convenience, the five blood pumps <b>104</b> in a bank are referred to numerically from one to five, where pump three is the middle pump of the bank, pumps two and four are the pumps adjacent to the middle pump, and pumps one and five are the outside pumps.

<figref idref="DRAWINGS">FIG. 15</figref> shows a process flow diagram describing the blood pump working solution priming process in accordance with an embodiment of the present invention. The priming process begins in block <b>1501</b>. In block <b>1502</b>, a put operation is performed on all five blood pumps. This removes as much air as possible from the working solution chambers of the pump cassettes <b>102</b>. Then, get operations are performed on the blood pumps, starting with pump three, in block <b>1503</b>, then pumps two and four simultaneously, in block <b>1504</b>, and then pumps one and five simultaneously, in block <b>1505</b>. Then, put operations are performed on the blood pumps, starting with pump three, in block <b>1506</b>, then pumps two and four simultaneously, in block <b>1507</b>, and then pumps one and five simultaneously, in block <b>1508</b>. Then, get operations are performed on the blood pumps, starting with pump three, in block <b>1509</b>, then pumps two and four simultaneously, in block <b>1510</b>, and then pumps one and five simultaneously, in block <b>1511</b>. Then, put operations are performed on the blood pumps, starting with pump three, in block <b>1512</b>, then pumps two and four simultaneously, in block <b>1513</b>, and then pumps one and five simultaneously, in block <b>1514</b>. Finally, get operations are performed on all five pumps simultaneously, in block <b>1518</b>. If a blood pump detects a “no flow” condition during any of the get and put operations, an error condition is raised in block <b>1516</b>, and priming is terminated. If a blood pump detects air in the working solution chamber after completion of the priming process, then an error condition is raised in block <b>1517</b>. The priming process ends in block <b>1518</b>.

Blood Pump Wet Cassette Integrity Test

The wet cassette integrity test (CIT) is used to identify defects within the injection-molded body of the cassette. The wet CIT involves testing the functionality of all of the fluid valves within the cassette as well as testing for “cross-talk” between the fluid paths and fluid pump chambers within the cassette. The wet CIT is performed on a partially primed cassette, after priming the working solution pump chamber, but before priming the RBC pump chamber. Therefore, a complete wet CIT is performed on the working solution pump chamber, but the RBC pump chamber is tested using air pressure and decay. Priming and wet testing of the RBC pump chamber is performed during blood mixing, as discussed below.

<figref idref="DRAWINGS">FIG. 16</figref> shows a process flow diagram describing the blood pump wet CIT process in accordance with an embodiment of the present invention. The wet CIT process begins in block <b>1601</b>, and involves three passes of blocks <b>1602</b> through <b>1619</b>. In each pass, the working solution line occluder <b>813</b> is retracted, in block <b>1602</b>, and various measurements are performed on both chambers, in block <b>1603</b>. If the measurements are outside of a predetermined threshold (NO in block <b>1604</b>), then an error signal is generated, in block <b>1605</b>. Otherwise, a chamber filling operation is performed, in block <b>1606</b>. During the first pass, both chambers are filled; during the second pass, only one chamber is filled; during the third pass, only the other chamber is filled. After the chamber filling operation, various measurements are performed on the chambers, in block <b>1607</b>. If the measurements are outside of a predetermined threshold (NO in block <b>1608</b>), then an error signal is generated, in block <b>1609</b>. At this point, the working solution line occluder <b>813</b> is left retracted during the first pass, but is closed during the second and third passes, in blocks <b>1610</b> and <b>1611</b>. The required fluid valves are then opened, in block <b>1612</b>, tank pressure is applied to the chambers for a predetermined amount of time, in block <b>1613</b>, and various measurements are performed on the chambers, in block <b>1614</b>. If the measurements are outside of a predetermined threshold (NO in block <b>1615</b>), then an error signal is generated in block <b>1616</b>. Otherwise, the process determines whether the volume displaced is within some threshold, in block <b>1617</b>. If not, then an error signal is generated, in block <b>1618</b>. After all three passes are complete, the working solution line occluder <b>813</b> is opened, in block <b>1620</b>, and both chambers are purged to the working solution bag, in block <b>1621</b>. The process ends in block <b>1622</b>.

Blood Mixing

The blood mixing process is performed essentially in three stages, namely a priming stage, a mixing stage, and a residuals stage. The priming stage involves priming the RBC pump chamber <b>334</b> from the RBCC bag <b>106</b>. The mixing stage involves repetitively drawing a quantity of working solution in to the working solution pump chamber <b>333</b> and drawing a quantity of RBCC through the channel <b>310</b> into the RBC pump chamber <b>334</b> while pulsing working solution from the working solution pump chamber <b>333</b> into the channel <b>310</b> so that the working solution and RBCC mix within the channel <b>310</b> and the RBC pump chamber <b>334</b>. The pulsing of working solution is dynamically adjusted so that the resulting incubation solution has a predetermined concentration of working solution, within certain limits. The mixing stage continues until air is detected in the RBCC inlet tube <b>204</b> by the air-in-line sensor <b>610</b>, signaling that there is no more RBCC to be processed. The residuals stage handles the residual contents in the RBC pump chamber <b>334</b> (if any) following the mixing stage. In the residuals stage, the concentration of working solution and RBCC in the RBC pump chamber <b>334</b> is measured, and the contents of the RBC pump chamber <b>334</b> are delivered to the incubation bag <b>118</b> if and only if the concentration of working solution and RBCC is within a predetermined specification. The overall concentration of working solution in the incubation solution is also measured, and a signal is generated to indicate whether or not the incubation solution is usable. The blood mixing process preferably prevents fluid from being pushed back into the working solution line after RBCC has been introduced into the pump cassette in order to prevent contamination of the working solution.

<figref idref="DRAWINGS">FIGS. 17A-D</figref> show a process flow diagram describing the blood mixing process in accordance with an embodiment of the present invention. The process begins in block <b>1701</b>, and proceeds to prime the RBC pump chamber <b>334</b>. Specifically, the RBC occluder <b>814</b> is opened, in block <b>1702</b>, and the contents of the RBC pump chamber <b>334</b> are purged to the RBCC bag <b>106</b>, in block <b>1703</b>. If a no flow condition is detected in block <b>1704</b>, then the process ends in failure in block <b>1705</b>. Otherwise, the RBC pump chamber <b>334</b> is filled from the RBCC bag <b>106</b>, in block <b>1706</b>. If a no flow condition is detected in block <b>1707</b>, then the process ends in failure in block <b>1705</b>. Otherwise, the contents of the RBC pump chamber <b>334</b> is purged back to the RBCC bag <b>106</b>, in block <b>1708</b>, and the volume of the RBC pump chamber <b>334</b> is computed, in block <b>1709</b>. If a no flow condition is detected in block <b>1710</b>, then the process ends in failure in block <b>1705</b>. If air is detected in the RBC pump chamber <b>334</b> in block <b>1711</b>, then an error signal is generated, in block <b>1712</b>, and a second attempt is made to prime the RBC pump chamber <b>334</b> by repeating blocks <b>1706</b> through <b>1711</b>. If air is again detected in the RBC pump chamber <b>334</b> in block <b>1711</b>, then the process ends in failure in block <b>1713</b>.

If the RBC pump chamber <b>334</b> is successfully primed, then the process continues with the mixing stage. Specifically, the working solution pump chamber <b>333</b> is filled from the working solution bag <b>112</b> with working solution, in block <b>1714</b>. The volume of the working solution pump chamber <b>333</b> is measured, in block <b>1715</b>. If air is detected in the working solution pump chamber <b>333</b> in block <b>1716</b>, then the process ends in failure in block <b>1717</b>. If a no flow condition is detected in block <b>1718</b>, then the process ends in failure in block <b>1719</b>.

The RBCC is then mixed with working solution, in block <b>1720</b>, specifically by drawing RBCC from the RBCC bag <b>106</b> through the channel <b>310</b> into the RBC pump chamber <b>334</b> while simultaneously pulsing working solution from the working solution pump chamber <b>333</b> into the channel <b>310</b> so that the working solution and RBCC are mixed within the channel <b>310</b> and the RBC pump chamber <b>334</b>. While this mixing is being performed, the process is monitoring for air in the RBCC inlet tube <b>204</b>, in block <b>1742</b>. Assuming no air is detected in the RBCC inlet tube <b>204</b>, in block <b>1742</b>, the volumes of both chambers <b>333</b> and <b>334</b> are measured, in block <b>1721</b>. If air is detected in the RBC pump chamber <b>334</b> in block <b>1722</b>, then the process ends in failure in block <b>1723</b>. If a no flow condition is detected in block <b>1724</b>, then the process ends in failure in block <b>1725</b>.

After mixing the working solution and RBCC, the concentration of working solution to RBCC in the RBC pump chamber <b>334</b> is calculated, in block <b>1726</b>, and a determination is made whether the concentration for this particular chamber is within predetermined specifications, in block <b>1727</b>. If the concentration of working solution to RBCC in the RBC pump chamber <b>334</b> is outside of specifications, then an error condition is signaled, in block <b>1728</b>. In any case, though, the pulse width is adjusted based upon the concentration of working solution to RBCC in the RBC pump chamber <b>334</b>, in block <b>1729</b>, and the contents of the RBC pump chamber <b>334</b> are delivered to the incubation bag <b>118</b>, in block <b>1730</b>. The volume of the RBC pump chamber <b>1731</b> is measured, in block <b>1731</b>. If a no flow condition is detected in block <b>1732</b>, then the process ends in failure in block <b>1733</b>.

In this first pass of the mixing stage, from block <b>1734</b>, the RBC pump chamber <b>334</b> is filled from the RBCC bag <b>106</b>, in block <b>1735</b>. If a no flow condition is detected in block <b>1736</b> while attempting to fill the RBC pump chamber <b>334</b> from the RBCC bag <b>106</b> then the process ends in failure in block <b>1737</b>. Otherwise, the contents of the RBC pump chamber <b>334</b> are purged to the RBCC bag <b>106</b>, in block <b>1738</b>, and the volume of the RBC pump chamber <b>334</b> is computed, in block <b>1739</b>. If a no flow condition is detected in block <b>1740</b> while attempting to purge the contents of the RBC pump chamber <b>334</b>, then the process ends in failure in block <b>1741</b>. Otherwise, the mixing stage continues by recycling to block <b>1714</b> and repeating blocks <b>1714</b> through <b>1734</b>. During the second and subsequent passes of the mixing stage, the process recycles from block <b>1734</b> to block <b>1714</b>, omitting blocks <b>1735</b> through <b>1741</b>.

When air is detected in the RBCC inlet tube <b>204</b>, in block <b>1742</b>, filling of the RBC pump chamber <b>334</b> with RBCC and working solution is aborted (preferably before air has entered the RBC pump chamber), in block <b>1743</b>, and a volume calculation is performed for both chambers, in block <b>1744</b>. If air is detected in the RBC pump chamber <b>334</b> in block <b>1745</b>, then the process ends in failure in block <b>1746</b>. Assuming that there is no air in the RBC pump chamber <b>334</b>, then the concentration of working solution to RBCC in the RBC pump chamber <b>334</b> is calculated, in block <b>1747</b>, and a determination is made whether the concentration for this particular chamber is within predetermined specifications, in block <b>1748</b>. If and only if the concentration of working solution to RBCC in the RBC pump chamber <b>334</b> is within specifications, the contents of the RBC pump chamber <b>334</b> are delivered to the incubation bag <b>118</b>, in block <b>1749</b>, the RBC pump chamber <b>334</b> is filled from the RBCC bag <b>106</b>, in block <b>1750</b>, and, upon detecting air in the RBC pump chamber <b>334</b> in block <b>1751</b>, the contents of the RBC pump chamber <b>334</b> are delivered to the incubation bag <b>118</b>, in block <b>1752</b>. Whether or not the residual contents of the RBC pump chamber <b>334</b> are delivered to the incubation bag <b>118</b>, the overall concentration of working solution to RBCC in the incubation solution is calculated, in block <b>1753</b>. If the overall concentration is outside of specifications, then an error condition is signaled, in block <b>1755</b>. In any case, process data is sent to the process controller <b>120</b>, in block <b>1754</b>. The process ends in block <b>1755</b>.

Manual Teardown

During normal blood pump teardown, the blood pump <b>104</b> receives commands from the process controller <b>120</b> to release pressure against the pump door so that the door can be opened by the operator. The pressure against the door comes from both the door piston bladder and the occluders. While the door piston bladder is pressurized and the tubing occluders are engaged, it is virtually impossible for the operator to open the pump door and remove the pump cassette. If communication between the process controller <b>120</b> and the blood pump <b>104</b> is lost, then the operator will need to relieve this pressure manually in order to remove the cassette. Among other things, this involves the operator pressing the manual door release valve on the back of the pump to deflate the bladder in the door assembly. The operator may also manually retract the occluders if necessary.

<figref idref="DRAWINGS">FIG. 19</figref> shows a process flow diagram describing the process for manual blood pump teardown in accordance with an embodiment of the present invention. The process starts in block <b>1901</b>. The operator is instructed to heat seal the incubation and working solution lines, in block <b>1902</b>. The blood pump <b>104</b> is then instructed to test the heat seal of the incubation line, in block <b>1903</b>. If the incubation line is not sealed, then the process enters anomaly handling, in block <b>1904</b>. Assuming the incubation line is sealed, then the blood pump <b>104</b> is instructed to test the heat seal of the working solution line, in block <b>1905</b>. If the working solution line is not sealed, then the process enters anomaly handling, in block <b>1906</b>. The blood pump <b>104</b> is instructed to release the door, in block <b>1907</b>, and the operator is instructed to press the manual door release valve on the back of the pump to deflate the bladder in the door assembly, in block <b>1908</b>, if the blood pump <b>104</b> does not release the door. The operator then manually retracts the occulders if necessary to allow opening of the door, in block <b>1909</b>. The operator then removes the blood disposables, in block <b>1910</b>. A close-case file is created indicating the failure, in block <b>1911</b>. The process ends in block <b>1912</b>.

Volumetric Calibration

The blood pump <b>104</b> is typically calibrated periodically to verify its ability to accurately measure volumes of pumped fluids. In exemplary embodiments of the invention, this calibration is done by running test measurements with two different test cassettes having different but known chamber volumes.

<figref idref="DRAWINGS">FIG. 18</figref> shows a process flow diagram describing the volumetric calibration process in accordance with an embodiment of the present invention. The process begins in block <b>1801</b>. The operator is instructed to scan a bar code on the blood pump <b>104</b> in block <b>1802</b> in order to test the blood pump <b>104</b>. The operator is then instructed to load the first test cassette, in block <b>1803</b>. Upon confirmation that the door is closed, in block <b>1804</b>, the door is sealed, in block <b>1805</b>. If the door fails to seal properly, then the process enters anomaly handling, in block <b>1806</b>. If the door seals properly, a dry CIT is run, in block <b>1807</b>. If the dry CIT fails, then the process enters anomaly handling, in block <b>1808</b>. If the dry CIT passes, then a volume calibration test is run to measure the volume of the chambers, in block <b>1809</b>. If the difference between the measured volume and the known volume of the first cassette is greater than or equal to some predetermined threshold, then the process enters anomaly handling, in block <b>1810</b>. Otherwise, the door is released, in block <b>1811</b>, and the operator is instructed to load the second test cassette, in block <b>1812</b>. Upon confirmation that the door is closed, in block <b>1813</b>, the door is sealed, in block <b>1814</b>. If the door fails to seal properly, then the process enters anomaly handling, in block <b>1815</b>. If the door seals properly, a dry CIT is run, in block <b>1816</b>. If the dry CIT fails, then the process enters anomaly handing; in block <b>1817</b>. If the dry CIT passes, then a volume calibration test is run to measure the volume of the chambers, in block <b>1818</b>. If the difference between the measured volume and the known volume of the second cassette is greater than or equal to some predetermined threshold, then the process enters anomaly handling, in block <b>1819</b>. Otherwise, a test pass determination is made, in block <b>1820</b>, and a report is printed, in block <b>1821</b>. The door is released, in block <b>1822</b>, and the operator is instructed to remove the second test cassette, in block <b>1823</b>. The process ends in block <b>1824</b>.

It should also be noted that the flow diagrams are used herein to demonstrate various aspects of the invention, and should not be construed to limit the present invention to any particular flow or implementation. In some cases, certain process steps can be omitted or performed in a different order than shown without changing the overall results or otherwise departing from the true scope of the invention.

The present invention may be embodied in other specific forms without departing from the true scope of the invention. The described embodiments are to be considered in all respects only as illustrative and not restrictive.